add a temp routine for speed testing of .match

src/core/Str.pm

@@ -366,6 +366,21 @@ my class Str does Stringy { # declared in BOOTSTRAP
             !! self.match(:g, :$x, $pat).map: { .Str }
     }
 
+    # A temporary routine for differential testing of .match overhead.
+    # This can only be used for a single non-multi match, and does not
+    # set $/.
+    method simplematch($pat) {
+        my $caller_dollar_slash := nqp::getlexcaller('$/');
+        my %opts;
+        %opts<c> = 0;
+        my $patrx := nqp::istype($pat,Code) ?? $pat !! / "$pat": /;
+        my $cur := $patrx(Cursor.'!cursor_init'(self, |%opts));
+
+        $cur.pos >= 0
+            ?? $cur.MATCH_SAVE
+            !! Nil;
+    }
+
     method match($pat,
                  :continue(:$c), :pos(:$p),
                  :global(:$g), :overlap(:$ov), :exhaustive(:$ex),